Roadway markers are used to delineate the roadway to drivers. They are particularly useful during inclement weather or at night. Markers are usually reflectors that reflect light back to oncoming vehicles. They may also be an independent, self-illuminating light source.
These markers are susceptible to damage. One of the main causes of damage has been snowplow blades. In the past protective castings have been developed to protect the marker. See U.S. Pat. Nos. 4,195,945 and 4,155,666. Currently, protective castings require a cut in the pavement to recess them, thereby minimizing their height above the roadway. Because of their bulk a considerable hole is required. This causes a weakening of the roadway surface that eventually causes the castings to be pushed down and rendered ineffective.
Other models sit on top of the road. These castings are higher than the recessed castings and consequently play havoc with snowplow machines.